Rigid disk data storage devices are ubiquitous in computer data processing systems and have become a highly competitive commodity product which must be economically produced in an environment of rapid technology advance and short product development cycles. Data integrity and device reliability must be retained while achieving both higher data areal densities and reduced device size. Enhanced structural designs enabled by improved fabrication techniques afford a competitive advantage in larger drives using a 31/2 inch or 21/2 inch form factor, but become essential as miniaturization progresses to the Personal Computer Memory Card Industry Association (PCMCIA) type II standard wherein the overall device size has respective approximate length and width dimensions of 31/4 and 2 inches and an overall height of 5 millimeters. In addition, it can be expected that even smaller devices will be used in the future.
No portion of the disk drive presents greater mechanical challenges than the actuator assembly wherein the transducer, which is moved rapidly from track to track during access and is maintained in precision alignment with an addressed track during data read and write operations, must be electrically connected to the arm electronics. The connecting lead wires, which carry the read/write electrical signals, are less than 0.002 inch in diameter and require attachment to both the transducer and the flex cable that electrically connects the actuator to the drive circuitry. Further, multiple leads are necessary for each transducer head since the state of the art device for enabling high density recording is the magnetoresistive (MR) head which is actually two transducer devices, an MR transducer for reading data and a thin film transducer for writing data. The attachment of lead wires to both the transducer head and the flex cable, previously accomplished by largely manual soldering techniques, has been enhanced by positioning and alignment structures and methods that better adapt to automatic fabrication using ultrasonic bonding. Such an improved process and structure is shown in U.S. Pat. No. 5,074,029 (Brooks, Jr. et al.) assigned to the assignee of the present invention.
The cited patent teaches the use of a plastic tail portion that is molded about the end of the transducer supporting load beam to provide a window across which the lead wires are strung and positioned to permit pivotal movement of the wires spanning the window into alignment with flex cable contact pads to achieve the electrical connections. The plastic tail portion is progressively removed from the load beam and following the ultrasonic welding of the lead portions spanning the window to the corresponding flex cable pads, the last portion is removed so that no part, of the tail portion forms a part of the final assembly. This structure and technique enables the multiple leads to be aligned and attached in a single operation using smaller pad areas. However, the use of an intermediate part not only increases the cost, but also the cumulative tolerances involved including the pivoting of the positioned leads requires that the alignment of wires and pads be carefully checked prior to the final welding attachment operation.